This invention generally relates to collapsible, reusable containers. More specifically, the invention relates to such containers that are especially well-suited for holding bulk, particulate materials, and to a method for loading a product into and unloading that product from a collapsible container.
Reusable, collapsible containers are being used with increasing frequency to ship bulk, particulate materials such as coffee beans, cereals, and gelatin powder. Typically, when in an expanded position or condition, these containers have a box shape and are designed to be stacked one on top of another. An advantage of such containers is that, when empty, they can be collapsed into a very compact shape in which the container occupies only a small portion of the space it occupies when in the expanded condition, and this keeps the cost of storing and transporting the containers themselves relatively low. A disadvantage of collapsible containers is that they often do not have the necessary rigidity to maintain their shape when used to hold dense products; and, for example, the sides of the container may bulge, or bow outwardly when the container is filled with such a product. This outward bulging may damage the container and may make it difficult or impossible to stack other containers on it.
For instance, one type of collapsible container includes an expandable outside member having four side panels foldably connected to a bottom section, and an expandable inside member having four reinforcing panels. In use, the outside member is opened so that this member forms a box that is open at one end; and the inside member is expanded and placed inside the outside member, with the reinforcing panels generally congruent and abutting against the side panels of the outside member so that the former panels support and reinforce the latter panels. The inside member also includes four top flaps, each one of which is foldably connected to a top edge of a respective one of the panels of the inside member.
The top flaps are positioned over the interior of the container; and, once the container is filled with product, a lid or cover is mounted on these top flaps, extending over the outside member of the container, to cover the product inside the container. If the side panels of the container bulge outwardly, those side panels may force the top flaps upward. If this occurs while the container is being filled, the flaps may prevent the lid from being properly seated on the container, and this may prevent this container from being used to support other containers. If the top flaps flip upward after the container is filled and covered, the flaps may tear the container lid, making it unsuitable for further use.